CN111556802A

CN111556802A - Heating device for thermoplastic resin sheet and method for producing thermoplastic resin molded body

Info

Publication number: CN111556802A
Application number: CN201880085438.0A
Authority: CN
Inventors: 布施充贵; 馆山胜; 西崎昭彦; 小平和久; 藤田久仁子
Original assignee: Toray Industries Inc
Current assignee: Toray Industries Inc
Priority date: 2018-01-12
Filing date: 2018-12-25
Publication date: 2020-08-18
Also published as: EP3738738A4; KR102588820B1; KR20200105653A; JPWO2019138862A1; WO2019138862A1; JP7229481B2; US20210069938A1; EP3738738A1; EP3738738B1; US11407148B2

Abstract

The heating device is a heating device for heating a thermoplastic resin sheet made of a thermoplastic resin, and is a heating device in which a wall surface of the heating device is indirectly heated by a saturated vapor of a heating medium, and a heating wall of the heating device has a lifting function, and the thermoplastic resin sheet is heated to a temperature equal to or higher than a melting point of the thermoplastic resin by contact of the thermoplastic resin sheet with the heating wall. The invention provides a heating device which can heat at high speed and has small temperature deviation when preheating, heating to a specified temperature and processing, and a method for manufacturing a high-quality thermoplastic fiber reinforced forming body by using the heating device.

Description

Heating device for thermoplastic resin sheet and method for producing thermoplastic resin molded body

Technical Field

The present invention relates to a heating device for a thermoplastic resin sheet and a method for producing a thermoplastic resin molded body using the heating device. More particularly, the present invention relates to an apparatus for heating a fiber-reinforced thermoplastic resin sheet to a predetermined temperature with good precision and uniformity when the sheet is heated, and a method for producing a molded article by press molding.

Background

The following techniques are widely known: a molded article having a desired shape is produced by using a molding material formed of a bundle-like aggregate of discontinuous reinforcing fibers (for example, carbon fibers) (hereinafter, sometimes referred to as a fiber bundle) and a matrix resin, and molding the molding material by heating and pressing.

In order to press-form a thermoplastic fiber-reinforced composite material comprising reinforcing fibers and a matrix resin, it is necessary to preheat and heat a thermoplastic resin sheet to a predetermined temperature to soften and melt the sheet. However, this method has a drawback that the heating time is long, and therefore, a radiation heating method of irradiating and heating electromagnetic waves in the infrared ray and far infrared ray regions to the thermoplastic resin sheet is widely used. A radiation type heating furnace for irradiating electromagnetic waves in the infrared or far infrared region is used as a heating furnace used for press forming, but a near infrared type heater tends to have a large heat flow rate at a high temperature and to have a low absorption efficiency for plastics. On the other hand, far infrared heaters tend to have a small heat flow rate at low temperatures but have a high absorption efficiency of plastics as compared with near infrared heaters, and far infrared heaters (hereinafter referred to as IR heaters) are often used as heaters for heating ovens.

In a heating furnace using an IR heater, the heater is generally arranged vertically, and the heater is controlled by dividing the heater into a plurality of zones, thereby achieving uniform heating. This method has advantages such as low cost of the heating furnace, good heating efficiency, and excellent maintainability, but has a disadvantage that the temperature variation of the object to be heated becomes large.

The preheating of the thermoplastic resin sheet varies depending on the wall thickness, and usually takes several minutes, and the preheating time occupies most of the molding cycle. Further, when variation occurs in heating of the thermoplastic resin sheet, the lowest temperature portion may need to be raised to a temperature equal to or higher than the melting point of the resin, and the moldability may be deteriorated due to an increase in the preheating time, and the physical property may be deteriorated due to excessive heating of the sheet to cause poor appearance, and thus an improvement in the method of heating the thermoplastic resin sheet is desired.

As one of the improvement methods, a continuous preheating furnace is used which automatically and continuously conveys a thermoplastic resin sheet by a conveyor belt in order to improve the moldability of press molding. However, the continuous heating type preheating furnace is configured such that it is difficult to completely seal the inlet and outlet of the thermoplastic resin sheet, and it is difficult to uniformly heat the thermoplastic resin sheet due to the influence of the external atmosphere.

The heating furnace is divided into a plurality of zones and optimized by changing the set temperature of the heaters for the purpose of uniformly heating the thermoplastic resin sheet, but the improvement is made because it is difficult to uniformly heat the entire large thermoplastic resin sheet due to complicated influences such as radiation from adjacent heaters, radiation from the walls of the preheating furnace, and a difference in surface area of the end portion of the base material.

Patent document 1 proposes: a method of controlling the temperature of a thermoplastic resin sheet by providing a temperature sensor in the vicinity of the outlet of a continuous heating furnace formed of a plurality of heaters to measure the temperature of a base material and adjusting the output of the heaters. In this method, temperature control of the measurement position of the sensor can be achieved, but there is no description about uniform heating of the entire sheet.

Prior patent literature

Patent document

Patent document 1 Japanese laid-open patent publication No. Sho 60-79916

Disclosure of Invention

Problems to be solved by the invention

Accordingly, an object of the present invention is to provide: a heating device capable of realizing high-speed heating with less temperature deviation when preheating and heating to a predetermined temperature for processing, and a method for producing a high-quality thermoplastic resin molded article using the heating device.

Means for solving the problems

In order to solve the above problem, the present invention has the following configuration.

(1) The heating device is a heating device for heating a thermoplastic resin sheet made of a thermoplastic resin, and is a heating device in which a wall surface of the heating device is indirectly heated by a saturated vapor of a heating medium, and a heating wall of the heating device has a lifting function, and the thermoplastic resin sheet is heated to a temperature equal to or higher than a melting point of the thermoplastic resin by contact of the thermoplastic resin sheet with the heating wall.

(2) The heating device according to (1), wherein the heating device has a self-induction function [ A ] of selectively heating at least a portion having a low temperature.

(3) The heating apparatus according to (1) or (2), wherein an organic compound is used as the heat medium.

(4) The heating apparatus according to (1) or (2), wherein an inorganic substance is used as the heat medium.

(5) A method for producing a thermoplastic resin molded article, characterized in that a thermoplastic resin sheet comprising a thermoplastic resin is heated to a temperature equal to or higher than the melting point of the thermoplastic resin by the heating device according to any one of (1) to (4) to melt the thermoplastic resin, and then press molding is performed, wherein the thermoplastic resin sheet is set in a molding die comprising an upper die and a lower die, and after the die is closed, the molding die is pressurized and cooled to solidify the sheet to obtain the thermoplastic resin molded article, the heating device is a heating device in which the wall surface of the device is indirectly heated by a saturated vapor of a heating medium, and the heating wall has a lifting function, and the thermoplastic resin sheet is heated to a temperature equal to or higher than the melting point of the thermoplastic resin sheet by the contact of the thermoplastic resin sheet.

(6) The method for producing a thermoplastic resin molded article according to item (5), wherein 2 or more sheets of the thermoplastic resin are simultaneously melted and heated by the heating device.

(7) The method for producing a thermoplastic resin molded article according to item (6), wherein the heating device has a self-induction function [ A ] of selectively heating at least a portion having a low temperature.

(8) The method for producing a thermoplastic resin molded body according to any one of (5) to (7), wherein the thermoplastic resin sheets having different heat capacities are arranged so as not to overlap and are melt-heated by the heating furnace.

(9) The method for producing a thermoplastic resin molded body according to any one of (5) to (7), wherein the thermoplastic resin sheets having different heat capacities are overlapped and melt-heated by the heating furnace.

(10) The method for producing a thermoplastic resin molded article according to any one of (5) to (9), wherein the thermoplastic resin sheet materials having different heat capacities are subjected to a press molding by heating and melting, and the thermoplastic resin sheet materials are stacked on a rib-shaped molding die including an upper die and a lower die, and the rib-shaped molding die is closed, pressurized, cooled, and solidified to obtain the rib-shaped thermoplastic resin molded article.

(11) The method for producing a thermoplastic resin molded body according to any one of (5) to (9), wherein the thermoplastic resin sheets having different heat capacities are subjected to a press molding in which the thermoplastic resin sheets are stacked on each other and placed in a convex-shaped molding die including an upper die and a lower die, and the die is closed, and then pressurized, cooled, and solidified to obtain the convex-shaped thermoplastic resin molded body.

(12) The method for producing a thermoplastic resin molded article according to any one of (5) to (11), wherein the thermoplastic resin sheet is a fiber-reinforced thermoplastic resin comprising a thermoplastic resin and reinforcing fibers.

(13) The method for producing a thermoplastic resin molded article according to item (12), wherein the reinforcing fibers contained in the thermoplastic resin sheet include at least 1 of carbon fibers, glass fibers, and aramid fibers.

Effects of the invention

According to the heating device for a thermoplastic resin sheet of the present invention, since the wall surface of the heating device is indirectly heated by the saturated vapor of the heating medium, the heating wall of the heating device has a lifting function, and the thermoplastic resin sheet is heated to the melting point of the thermoplastic resin or more by the contact of the thermoplastic resin sheet with the heating wall, the temperature deviation is small when the thermoplastic resin sheet is heated, and the heating can be performed at a high speed.

Further, since the thermoplastic resin sheet is heated by using the heating device, even if the thermoplastic resin sheets have different volumes, 2 or more thermoplastic resin sheets can be uniformly heated at the same time, and a molded body having a complicated three-dimensional shape such as a rib shape or a boss shape can be manufactured.

Drawings

Fig. 1 is a diagram showing the overall configuration of a heating apparatus according to the present invention.

Fig. 2 is a sectional view of the heating apparatus showing a section a-a' of fig. 1.

Fig. 3 is a sectional view of the heating apparatus showing a section B-B' of fig. 1.

Fig. 4 is a sectional view of the heating apparatus showing a section C-C of fig. 1.

Fig. 5 is a schematic view showing a temperature measurement material.

Fig. 6 is a schematic view showing a molding material.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the present invention is not limited to the form of the drawings. First, the heating device will be explained.

Fig. 1 is an overall configuration diagram showing an outline of a sheet heating apparatus according to an embodiment of the present invention, and fig. 2 is a schematic side sectional view of the heating apparatus. In these figures, 101 denotes a heating device, 102 denotes a heating device cabinet, 103 denotes an operation/control panel, 104 denotes a door, 105 denotes a base material lead-in portion, 106 denotes a slide portion, 107 denotes a heating upper wall elevation cylinder, 201 denotes an upper jacket, 202 denotes a lower jacket, 203 denotes a heat medium, 204 denotes saturated steam, 205 denotes a heater for heating the heat medium, 206 denotes a temperature sensor, 207 denotes a heating upper wall surface, 208 denotes a heating lower wall surface, 209 denotes a heating chamber, 201 denotes an incubator, and 211 denotes a thermoplastic resin sheet (base material).

The heating apparatus 101 includes upper and lower 2

magazines

201 and 202 for storing the heat medium, the upper magazine has a function of moving up and down, and the heating wall surface is configured to be in contact with the substrate. The shape of the jacket is matched with the shape and size of the thermoplastic resin sheet to be heated, and can be adapted to various shapes. The casing 201 may be configured to operate in a direction other than the vertical direction.

The heating device 101 is a heating device in which the wall surface of the heating device is indirectly heated by saturated vapor of the heat medium (heating device of heat medium vapor phase heating system), and is a heating device in which the upper wall and the lower wall are heated to heat the thermoplastic resin sheet to a temperature equal to or higher than the melting point of the thermoplastic resin by bringing the thermoplastic resin sheet into contact with the heating wall. A heating device using a heat medium gas phase heating method belongs to a pressure vessel, and is provided with a safety device as a pressure vessel (jacket). The pressure of the saturated vapor of the heat medium inside the jacket is kept constant by a pressure detection type safety device that detects the internal pressure of the jacket and operates the micro switch in an operating temperature region, whereby the temperature inside the jacket becomes constant.

The heating device 101 is formed in a box shape and has an opening on the front side. The opening is provided with a door 104 and a slide mechanism, and the opening and closing is performed by sliding the door, so that the thermoplastic sheet can be smoothly taken out. The sliding portion 106 includes 2 pairs of fixed rails and movable rails. The fixed rail and the movable rail are formed into a plate shape and attached to the lower part of the door, and the fixed rail is also formed into a plate shape and attached to the heating device cabinet. The movable rail is fitted into the fixed rail and supported by the fixed rail so as to be slidable in the front-rear direction.

Further, the substrate lead-out/introduction portion 105 may be provided in the gate portion, and the substrate may be smoothly installed in the heating chamber 209 by placing the substrate on the substrate lead-out/introduction portion 105.

An upper jacket 201 and a lower jacket 202 are provided above and below the heating chamber 209, and a heat medium 203 used in the heat medium vapor phase heating system is housed in the upper jacket 201 and the lower jacket 202. A heater 205 for heating a heat medium is provided inside the upper jacket 201 and the lower jacket 202, and the heat medium 203 is heated by the heater 205 for heating a heat medium and vaporized to form a saturated vapor 204.

The heat medium vapor phase heating method is a heating method using saturated vapor 204 of the heat medium 203, and is a heating method in which the heat medium is vaporized by heating the heat medium with the heat medium heating heater 205, and the temperature of the

heating walls

207 and 208 can be made uniform by keeping the temperature in the upper jacket 201 and the lower jacket 202 constant.

An electric heater or the like can be used as the heat medium heating heater 205. The heat medium 203 is heated by the heat medium heating heater 205, the temperature of the gas phase portion of the heat medium is measured by the temperature sensor, and the temperature control is performed by repeating the ON/OFF operation of the heater, so that the inside of the upper jacket 201 and the lower jacket 202 is maintained at a temperature at which the saturated vapor pressure is obtained.

As the heat medium 203 of the heat medium gas phase heating heater used in the heating apparatus 101 of the present invention, an organic compound or an inorganic substance can be used according to the use temperature range.

Examples of the organic compound include polyhydric alcohols (e.g., glycerin and polyethylene glycol), phenols and phenol ethers (e.g., anisole, diphenyl ether, and phenols), polyphenyls (e.g., terphenyl), chlorinated benzenes and polyphenyls (e.g., o-dichlorobenzene, polychloropolyphenyl, and Kanechlor (japanese: カネクロール)), silicates (e.g., Tetraallyl silicate), fractionated tar and petroleum (e.g., naphthalene derivatives and mineral oil).

Examples of the inorganic substance include a molten salt and a molten metal (alloy), and examples of the molten salt include a nitrate-based, a carbonate-based, and a chloride-based, and examples of the molten metal include Hg, Na — K (alloy), Pb, and Pb — Bi (eutectic mixture).

In the contact heat medium gas-phase heating method employed in the heating apparatus 101 of the present invention, since the test object is heated by being brought into contact with the wall surface indirectly heated by the heat medium saturated vapor, the so-called self-induction function [ a ] can be performed in which the saturated vapor 204 is condensed at a low temperature portion of the test object and energy is selectively supplied to a portion requiring energy.

That is, the heating device 101 is a heating device in which the wall surface of the heat medium heating device is indirectly heated by the saturated vapor of the heat medium, and when heating the thermoplastic resin sheet 211, the sheet can be heated to the target temperature by the self-induction function without excessively heating the thermoplastic resin sheet 211 to the set temperature or higher.

The peripheries of the upper and

lower cases

201 and 202 are surrounded by an insulation case 210 using an insulation material in order to improve temperature uniformity and reduce energy loss, in addition to heating the wall surfaces.

The upper jacket 201 of the heating apparatus 101 is vertically movable by the heating upper wall elevating cylinder 107, and the heating upper wall surface 207 can be brought into contact with the substrate. Since the substrate can be freely lifted and lowered in the vertical direction, the thickness of the substrate can be adjusted to any thickness. The air cylinder 107 may be attached to both sides of the jacket.

Next, as the thermoplastic resin sheet 211 of the present invention, a thermoplastic resin may be used as a matrix resin and a reinforcing fiber may be included.

The type of the reinforcing fiber is not particularly limited, and preferably at least 1 selected from the group consisting of carbon fiber, aramid fiber, and glass fiber. These can be used alone, also can be used in combination of more than 2. Among these, carbon fibers are particularly preferable because they can provide a composite material that is lightweight and has excellent strength. The carbon fiber may be either PAN-based or pitch-based, and the average fiber diameter is preferably 3 to 12 μm, more preferably 6 to 9 μm.

When reinforcing fibers are used, it is preferable to perform surface treatment for the purpose of improving adhesion to a matrix resin when the reinforcing fiber composite material is produced. As a method of surface treatment, there are electrolytic treatment, ozone treatment, ultraviolet treatment, and the like. The sizing agent may be added for the purpose of preventing fuzzing of the reinforcing fibers, improving the bundling property of the reinforcing fiber strands, improving the adhesion to the matrix resin, or the like. The sizing agent is not particularly limited, and compounds having a functional group such as an epoxy group, a urethane group, an amino group, or a carboxyl group can be used, and 1 or 2 or more of them can be used in combination.

The amount of solid deposited as a sizing agent is 0.01 wt% or more, more preferably 0.1 wt% or more, particularly preferably 0.15 wt% or more, preferably less than 4 wt%, further preferably less than 3 wt%, particularly preferably less than 2 wt%. When the amount of the sizing agent attached is less than 0.01 wt%, the surface adhesiveness between the matrix and the carbon fiber tends to be lowered when the composite material is produced, and the mechanical properties of the composite material are also likely to be lowered. On the other hand, if the amount of the sizing agent attached exceeds 4 wt%, the adhesion between the matrix and the carbon fibers tends to be adversely affected.

The form of the reinforcing fibers is not particularly limited, and continuous fibers are preferable, or discontinuous fibers obtained by chopping may be used. These can be used alone, also can be used in combination of more than 2.

In the case of continuous fibers, the fibers are laminated in any lamination configuration such as quasi-isotropic, alternate 0 °/90 ° lamination, random lamination, or the like, with the direction of the reinforcing fibers being one direction, to form a laminate. As the prepreg constituting the laminate, only a non-slit prepreg, only a slit prepreg, or both a non-slit prepreg and a slit prepreg may be used. In view of the ease of handling at this time, a laminate may be produced by laminating prepregs forming adjacent layers while spot-welding them by an ultrasonic welding machine.

In the laminate usable in the method for producing a thermoplastic resin molded article of the present invention, it is preferable to laminate a plurality of prepregs so that the direction of the reinforcing fibers becomes quasi-isotropic, from the viewpoint of reducing the anisotropy of flow at the time of pressing. The laminated structure preferably has quasi-isotropy (n is an integer of 1 or more, and s is a symmetrical laminated structure) expressed by a structure in which 4 layers of 0 °/45 °/90 °/45 °/ns are symmetrically laminated n times, and a structure in which 3 layers of 0 °/60 °/ns are symmetrically laminated n times (0 °/60 °/ns). By forming the quasi-isotropy, the warpage of the laminate can be suppressed. In addition, when molding is performed to produce a fiber-reinforced composite used as a structural material, it is necessary to withstand loads from a plurality of directions. From the viewpoint of mechanical properties, the fiber-reinforced composite is preferably laminated to be quasi-isotropic in order to withstand normal use.

In the case of chopped fibers, the chopped fibers are preferably randomly oriented in 2-dimensions in the plane. By randomly orienting the 2-dimensional structure, a molded article having small anisotropy of physical properties and small variation in molding warpage can be obtained during molding.

The weight-average fiber length of the chopped fibers is preferably 5mm or more, more preferably 6mm or more, particularly preferably 10mm or more, preferably 100mm or less, more preferably 50mm or less, and further preferably 25mm or less. When the weight-average fiber length of the carbon fibers is less than 5mm, the mechanical properties of the fiber-reinforced resin molding material are deteriorated. On the other hand, when the weight-average fiber length of the carbon fiber exceeds 100mm, moldability is lowered.

As the resin component constituting the thermoplastic resin sheet, a thermoplastic resin needs to be used. The thermoplastic resin can be molded in a short time and has excellent productivity because it can be cooled and solidified without involving a chemical reaction to obtain a predetermined shape. Further, a thermoplastic resin having a higher toughness value than a thermosetting resin is generally used, and strength, particularly impact resistance, can be improved. As the thermoplastic resin having such characteristics and suitable for the present invention, for example, the following resins can be mentioned: examples of the resin include polyethylene terephthalate (PET) resin, polybutylene terephthalate (PBT) resin, polytrimethylene terephthalate (PTT) resin, polyethylene naphthalate (PEN) resin, polyester such as liquid crystal polyester resin, polyolefin such as Polyethylene (PE) resin, polypropylene (PP) resin, polybutylene resin, and styrene resin, and in addition, Polyoxymethylene (POM) resin, Polyamide (PA) resin, Polycarbonate (PC) resin, polymethyl methacrylate (PMMA) resin, polyvinyl chloride (PVC) resin, Polyphenylene Sulfide (PPs) resin, polyphenylene ether (PPE) resin, modified PPE resin, Polyimide (PI) resin, Polyamideimide (PAI) resin, polyether imide (PEI) resin, Polysulfone (PSU) resin, modified PSU resin, polyether sulfone resin, Polyketone (PK) resin, polyether ketone (PEK) resin, polyethylene terephthalate (PTT) resin, polyethylene naphthalate (PEN) resin, polyethylene naphthalate (, And a thermoplastic elastomer such as a polyether ether ketone (PEEK) resin, a polyether ketone (PEKK) resin, a Polyarylate (PAR) resin, a polyether nitrile (PEN) resin, a phenol resin, a phenoxy resin, and a polytetrafluoroethylene resin, a polystyrene resin, a polyolefin resin, a polyurethane resin, a polyester resin, a polyamide resin, a polybutadiene resin, a polyisoprene resin, and a fluorine resin, a copolymer or a modified product thereof, and a resin obtained by blending 2 or more kinds thereof. In particular, a PPS resin is more preferably used from the viewpoint of heat resistance and chemical resistance, a polycarbonate resin and a styrene resin are more preferably used from the viewpoint of appearance and dimensional stability of a molded article, and a polyamide resin is more preferably used from the viewpoint of strength and impact resistance of the molded article. When polyamide is used as the thermoplastic resin, it is more preferable to blend an inorganic antioxidant in the polyamide.

By adding an inorganic antioxidant to a thermoplastic resin, the heat resistance is improved, whereby oxidative deterioration of the resin during heating of the base material during molding can be prevented, and the surface appearance of the molded article and the strength of the molded article can be further improved.

The amount of the inorganic antioxidant is preferably 0.01 to 1 part by weight based on 100 parts by weight of the polyamide. When the amount is less than 0.01 part by weight, the effect of improving heat resistance is hardly obtained, and when the amount is more than 1 part by weight, no significant improvement is obtained.

As the inorganic antioxidant, an antioxidant composed of a copper halide or a derivative thereof can be exemplified, and particularly, an effect of improving heat resistance can be exhibited by using copper iodide for polyamide.

The method for impregnating the reinforcing fibers with the matrix resin is not particularly limited, and when the method for impregnating the thermoplastic resin is exemplified, the impregnation of the reinforcing fibers with the thermoplastic resin as the matrix resin may be performed using an impregnation press. The press machine is not particularly limited as long as it can realize the temperature and pressure necessary for impregnation of the matrix resin, and a general press machine having a planar platen which can be moved up and down, or a so-called double-track press machine having a mechanism for moving 1 pair of endless steel belts can be used. In this impregnation step, the matrix resin may be formed into a film, a sheet such as a nonwoven fabric or a woven fabric, and then laminated with the discontinuous fiber mat, and in this state, the matrix resin may be melted and impregnated by using the press or the like, or the particulate matrix resin may be dispersed on the reinforcing fibers to form a laminate, or the particulate matrix resin may be dispersed and mixed into the mat while the chopped fibers are dispersed.

The content of the reinforcing fiber in the fiber-reinforced resin molding material is preferably 20 to 70 vol% of the entire volume. When the content of the reinforcing fiber is reduced, the mechanical properties of the fiber-reinforced resin molding material tend to be reduced. On the other hand, when the content of the reinforcing fiber is too large, the mechanical properties of the fiber-reinforced resin molding material tend to be improved, but the moldability tends to be lowered. The content of the reinforcing fiber in the fiber-reinforced resin molding material is more preferably 25 to 50 vol%.

Next, a method for producing a thermoplastic resin molded body using the heating device 101 will be described. First, the heating medium 203 in the heating apparatus 101 is heated in advance to raise the temperature of the heating chamber 209. The heated heating device 101 drops the thermoplastic resin sheet 211 on the heated lower wall surface 208, lowers the upper jacket 201, brings the heated upper wall surface 207 and the heated lower wall surface 208 into contact with the thermoplastic resin sheet 211, and heats the thermoplastic resin sheet 211 to a temperature equal to or higher than the melting point thereof by heat conduction to melt the thermoplastic resin sheet 211.

When the thermoplastic resin sheet 211 is fed into the heating chamber 209, the thermoplastic resin sheet 211 may be directly placed on the lower heating wall surface 208, or the base material lead-out/introduction portion 105 may be provided and the thermoplastic resin sheet 211 may be placed thereon and fed in consideration of mold release properties when the heated molten resin sheet is taken out from the heating apparatus 101 and the ease of taking out. The material used for the base material lead-out and introduction portion 105 is not particularly limited, and a material that does not deform or melt in a heating temperature range, such as a metal sheet or a resin sheet, may be selected. As the metal sheet, a metal sheet processed as a flat plate, a wire mesh, a punched metal, or an embossed metal may be used. When the base material introducing portion 105 is used, the larger the contact area with the thermoplastic resin sheet, the smaller the temperature deviation, and the higher the mold releasability, the higher the contact area. It can be freely selected in consideration of the balance of molding cycle, temperature accuracy, and the like.

In the method for producing the thermoplastic resin molded article, when the heating device 101 heats the thermoplastic resin sheet 211 to a temperature equal to or higher than the melting point of the thermoplastic resin, 1 or 2 or more thermoplastic resin sheets 211 may be simultaneously melted and heated. When 2 or more sheets 211 of the thermoplastic resin are heated at the same time, the volume and specific heat of the sheets may be the same or different. In a normal heating apparatus, when 2 or more sheets are heated simultaneously, if the volumes and specific heats of the thermoplastic resin sheets to be fed are different, a temperature difference occurs between the sheets. If a temperature difference occurs between the thermoplastic resin sheets, it is necessary to raise the temperature of the lowest temperature portion of the thermoplastic resin sheet having a low temperature to the melting point of the resin or higher, and the preheating time increases in the high temperature portion, which causes a decrease in physical properties and a poor appearance due to excessive heating.

When 2 or more thermoplastic resin sheets 211 are heated by the heating device 101 at the same time, the thermoplastic resin sheets 211 may be arranged so as not to overlap with each other and heated, or may be heated while overlapping with each other. When the thermoplastic resin sheets 211 are overlapped and heated, a part of the thermoplastic resin sheets may be overlapped or the whole surface may be overlapped. In a general heating apparatus, when only a part of thermoplastic resin sheets is overlapped and heated, a temperature rise is slow in the overlapped part of the thermoplastic resin sheets, a temperature difference is generated between the overlapped part and the non-overlapped part, and excessive heating is generated in the non-overlapped part, which causes a decrease in physical properties and a failure in appearance. In the heating apparatus 101 of the heat medium gas phase heating system according to the present invention, even when only a part of the heating apparatus is overlapped and heated, uniform heating is possible due to the unique self-induction function of the heat medium gas phase heating system. Further, even if the substrates having different capacities and specific heats are stacked in advance and heated, the stacking step can be omitted when filling the mold with the substrate after heating, and the temperature of the heated substrate can be prevented from being lowered, thereby shortening the cycle time.

The thermoplastic resin molded article can be obtained by taking out the molten thermoplastic resin sheet 211 heated to the melting point or higher by the heating device 101 from the heating device 101, and then performing press molding in which the thermoplastic resin sheet 211 is set in a molding die including an upper die and a lower die, and after the die is closed, the sheet is pressurized, cooled, and solidified.

When the press molding is performed, the curing temperature of the thermoplastic resin sheet 211 is Tc, which is preferably Tc-10 ℃ or lower and 25 ℃ or higher, with respect to the mold temperature of the molding die. The higher the mold temperature, the better the moldability, and the lower the mold temperature, the better the molding stability such as the warpage of the molded article.

In addition, in the case of press forming, the pressing force is 0.1MPa or more, preferably 0.5MPa or more, and more preferably 1MPa or more, and 40MPa or less, preferably 20MPa or less, and more preferably 10MPa or less, from the viewpoint of facility and base material fluidity. If the pressure is less than 0.1MPa, the thermoplastic resin sheet 211 cannot be sufficiently pressurized, and defects such as insufficient filling (short shot), occurrence of bubbles, deterioration of surface quality, and deterioration of physical property appearance rate may occur. If the pressure exceeds 40MPa, a large press facility and a high-strength mold may be required, and if the thermoplastic resin sheet contains reinforcing fibers, the reinforcing fibers may break and the physical property expression rate may deteriorate.

The shape of the mold described above may be a flat plate or a three-dimensional shape having a complicated shape. In particular, the features of the heating device of the present invention can be utilized to the maximum extent in molding the shape having the ribs and the bosses. In the heating apparatus 101, even when a thermoplastic resin sheet having a volume corresponding to a rib or a land shape portion is laminated on a thermoplastic resin sheet and 2 or more thermoplastic resin sheets having different volumes, specific heat and heat capacities are simultaneously heated while maintaining this state, the temperature of a low-temperature portion can be selectively raised by the self-induction function [ a ] and excessive heating can be prevented, so that heating without a temperature difference can be realized and the laminated heating base material can be set on a molding die as it is, and thus the rib or the land shape can be easily molded, and further, deterioration in physical properties and appearance defects due to excessive heating can be prevented in the heating apparatus 101. Further, since the number of lamination steps when the thermoplastic resin sheet is set in the mold can be reduced, the molding cycle can be shortened, cost reduction can be expected, and molding defects caused by cooling of the thermoplastic resin sheet before setting in the mold can be prevented. According to the method of the present invention, by molding the thermoplastic resin sheet under the above-described conditions using the heating device, a thermoplastic resin molded article having a three-dimensional complicated shape such as a high rib shape and the like which is extremely excellent in physical properties and surface appearance can be obtained.

Examples

Next, examples of the present invention and comparative examples will be described. The present invention is not limited to the present embodiment and comparative example.

(1) Using raw materials

Fiber [ F ]: a continuous carbon fiber bundle (manufactured by ZOLTEK, "PX 35 (registered trademark)") having a fiber diameter of 7.2 μm, a tensile elastic modulus of 240GPa, and a filament count of 50,000 filaments was used.

Matrix resin [ M ]: a polyamide resin ("Amilan (registered trademark) CM 1001", manufactured by Toray Industries, inc.).

(2) Preparation of the substrate

The fiber [ F ] was continuously inserted into a rotary cutter having a cutting blade inclined at an angle of 15 degrees with respect to the longitudinal direction of the fiber bundle to cut the fiber bundle, thereby obtaining a chopped fiber bundle [ A ] having a fiber length of 12.7mm, a width of 1mm, a thickness of 0.1mm, and a fiber count of 1000.

Following the cutting step, the chopped fiber bundles [ A ] are cut]The dispersion was carried out in a uniformly dispersed manner to obtain a random mat in which the fiber orientation was isotropic. The resulting discontinuous fiber mat had a basis weight of 1270g/m²。

The discontinuous fiber mat thus obtained was impregnated with the matrix resin [ M ] by pressing with a press at 280 ℃ and 3MPa for 5 minutes, and then cooled to obtain a base material of a fiber-reinforced thermoplastic resin composite material.

(3) Vf (carbon fiber content in fiber-reinforced resin Molding Material)

About 2g of a sample was cut out from the press-molded substrate, and the mass thereof was measured. Thereafter, the sample was heated in an electric furnace heated to 500 ℃ for 1 hour to burn off organic substances such as matrix resins. After cooling to room temperature, the mass of the remaining carbon fibers was measured. The mass ratio of the carbon fibers to the mass of the sample before burning out the organic matter such as the matrix resin was measured, and the content (%) of the carbon fibers was calculated. The volume content of the sample used in this case was 35 vol% (vol%).

(4) Heating device used

The following 3 types were used: a heating device (IR) based on a far infrared heater system; and a gas phase heating device (gas phase heating 1) which is a heating medium gas phase heating mode, does not have a lifting function on the upper part of the jacket box and heats only by radiation heat conduction; a gas phase heating device (gas phase heating 2) of a heating medium gas phase heating system, wherein the upper jacket has a lifting function and can perform contact heating from the upper part and the lower part.

(5) Method for measuring temperature of heated substrate

2 kinds of substrates of 180 mm. times.180 mm. times.2 mmt (material a) and 180 mm. times.120 mm. times.2 mm (material b) were used. The front and back surfaces of the base material were equally divided into 60mm × 60mm regions, thermocouples were provided at the centers of the regions, the objects (fig. 4) thus obtained were arranged in parallel or stacked, and the base material was put into an IR heating apparatus heated to a heater temperature of 320 ℃ and gas phase heating 1 and 2 heated to 290 ℃ to measure the surface layer temperature and the inner layer temperature of the base material. The temperature deviation of the entire substrate when it reached 280 ℃ and the time taken to reach 280 ℃ were evaluated.

(6) Evaluation of deterioration of substrate

The thermal degradation of nylon 6 by heating was evaluated by the relative viscosity (hereinafter referred to as η r). Since the molecular weight decreases and the relative viscosity decreases when nylon 6 is thermally decomposed, the ratio of η r before heating to η r after heating was obtained and evaluated as the η r retention ratio

η r retention (%) after heating η r/η r × 100 before heating

The heated η r measurement sample was quenched with water and solidified, and then divided into 3 parts in the thickness direction, and the samples for analysis were cut out at the surface layer portion and the central portion. The cut sample for analysis was vacuum-dried, dissolved in 98% sulfuric acid, and then filtered to remove carbon fibers. The obtained sulfuric acid solution was measured with an Ostwald viscometer to calculate η r.

(7) Formability evaluation (Press Molding)

Using a flat plate having a lower die of 400mm (length) × 300mm (width) and an upper die of 400mm (length) × 300mm (width) having grooves of 40mm in height, 1 ° in angle and 2mm in rib root width at the center position in the longitudinal direction, 2 kinds of base materials of 40mm (length) × 270mm (width) × 2mm (thickness) and 360mm (length) × 270mm (width) × 2mm (thickness) were used, and after parallel or superposed and heated so that the central temperature of the base materials (the temperature between two superposed pieces) was 280 ℃, a laminate 601 (fig. 6) of the molding material laminated with 2 base materials was placed at the center of the aforementioned die heated to 150 ℃, and pressurized at 2.5MPa for 30 seconds, and the determination was made by the following criteria: whether the mold area (400mm × 300mm) and the rib shape were completely filled and no surface resin ablation was present (o: a level that was not problematic in actual use), or an unfilled portion was generated, or a surface ablation was generated (x: a level that was problematic in actual use).

Comparative example 1

Using IR for the heating apparatus, 2 sheets of material a were aligned and heated, and the temperature deviation, temperature rise time, η r retention ratio, and moldability at this time were evaluated. As a result, a temperature variation of 10 ℃ at maximum occurs in the substrate, and it takes 4.5 minutes to raise the temperature, resulting in a large temperature variation. Regarding the η r retention, the surface layer was 68.9%, and the inner layer was 71.7%, which resulted in resin deterioration on the surface of the substrate. Further, resin ablation occurred in a part of the molded article, and moldability was evaluated as x. From these results, the evaluation was x (level of trouble in practical use).

Comparative example 2

Each item was evaluated in the same manner as in comparative example 1, except that the material lamination method was overlapped. As a result, a maximum temperature variation of 13 ℃ occurs in the substrate, and it takes 7 minutes to raise the temperature, resulting in a large temperature variation. With respect to η r retention, the surface layer was 64.5% and the inner layer was 72.4%, resulting in resin deterioration on the surface of the substrate. Further, resin ablation occurred in a part of the molded article, and moldability was evaluated as x. From these results, the evaluation was x (level of trouble in practical use).

Comparative example 3

Each item was evaluated in the same manner as in comparative example 1, except that the material a and the material b were used as the materials. As a result, a temperature variation of 15 ℃ at maximum occurs in the substrate, and it takes 4.5 minutes to raise the temperature, resulting in a considerable temperature variation. With respect to η r retention, the surface layer was 67.5% and the inner layer was 72.4%, and resin deterioration occurred on the surface of the substrate. In addition, resin ablation and unfilled portions of the rib portion of the molded article occurred, and moldability was evaluated as x. From these results, the evaluation was x (level of trouble in practical use).

Comparative example 4

Each item was evaluated in the same manner as in comparative example 3, except that the material lamination method was overlapped. As a result, a temperature variation of 20 ℃ at maximum occurs in the substrate, and it takes 6.5 minutes to raise the temperature, resulting in a considerable temperature variation. With respect to the η r retention rate, the surface layer was 63.0%, and the inner layer was 70.1%, resulting in resin deterioration on the surface of the substrate. In addition, the molded article had resin ablated and unfilled in the rib portion, and the moldability was evaluated as X. From these results, the evaluation was x (level of trouble in practical use).

Comparative example 5

Evaluation of each item was performed in the same manner as in comparative example 1 except that the gas phase heating 1 was used as the heating apparatus. As a result, a temperature deviation of 3 ℃ at maximum occurs in the substrate, and it takes 15 minutes to raise the temperature, and a considerable time is required to raise the temperature. The η r retention was good at 72.0% for the surface layer and 72.1% for the inner layer. Further, the molded article was completely filled, and no resin ablation was observed, and the moldability was evaluated as ≈ o. From these results, the evaluation was x (level of trouble in practical use).

Comparative example 6

Each item was evaluated in the same manner as in comparative example 5, except that the material lamination method was overlapped. As a result, a temperature deviation of at most 3 ℃ occurs in the substrate, and it takes 20 minutes to raise the temperature, and a considerable time is required to raise the temperature. The η r retention was good at 71.6% for the surface layer and 71.7% for the inner layer. Further, the molded article was completely filled, and no resin ablation was observed, and the moldability was evaluated as ≈ o. From these results, the evaluation was x (level of trouble in practical use).

Comparative example 7

Each item was evaluated in the same manner as in comparative example 5, except that the materials a and b were used as the materials. As a result, a temperature deviation of 2 ℃ at maximum occurs in the substrate, and it takes 12 minutes to raise the temperature, and a considerable time is required to raise the temperature. The η r retention was good at 70.5% for the surface layer and 70.9% for the inner layer. Further, the molded article was completely filled, and no resin ablation was observed, and the moldability was evaluated as ≈ o. From these results, the evaluation was x (level of trouble in practical use).

Comparative example 8

Evaluation of each item was performed in the same manner as in comparative example 7, except that the material lamination method was overlapped. As a result, a temperature deviation of 3 ℃ at maximum occurs in the substrate, and it takes 16 minutes to raise the temperature, and a considerable time is required to raise the temperature. The η r retention was good at 71.2% for the surface layer and 71.5% for the inner layer. Further, the molded article was completely filled, and no resin ablation was observed, and the moldability was evaluated as ≈ o. From these results, the evaluation was x (level of trouble in practical use).

(example 1)

Evaluation of each item was performed in the same manner as in comparative example 1 except that the gas phase heating 2 was used as the heating apparatus. As a result, a temperature variation of 2 ℃ at maximum occurred in the substrate, 3 minutes was required until the temperature was raised, and both the temperature variation and the temperature raising time were good. The η r retention was good at 72.2% for the surface layer and 72.4% for the inner layer. Further, the molded article was completely filled, and no resin ablation was observed, and the moldability was evaluated as ≈ o. From these results, the evaluation was evaluated as ∘ (a level at which there was no problem in actual use).

(example 2)

The evaluation of each item was performed in the same manner as in example 1, except that the material lamination method was overlapped. As a result, a temperature variation of 2 ℃ at maximum occurred in the substrate, 4 minutes was required until the temperature was raised, and both the temperature variation and the temperature raising time were good. The η r retention was good at 73.6% for the surface layer and 73.7% for the inner layer. Further, the molded article was completely filled, and no resin ablation was observed, and the moldability was evaluated as ≈ o. From these results, the evaluation was evaluated as ∘ (a level at which there was no problem in actual use).

(example 3)

Each item was evaluated in the same manner as in example 1, except that the material a and the material b were used as the materials. As a result, a temperature variation of 3 ℃ at maximum occurred in the substrate, 3 minutes was required until the temperature was raised, and both the temperature variation and the temperature raising time were good. The η r retention was good at 73.1% for the surface layer and 73.4% for the inner layer. Further, the molded article was completely filled, and no resin ablation was observed, and the moldability was evaluated as ≈ o. From these results, the evaluation was evaluated as ∘ (a level at which there was no problem in actual use).

(example 4)

The evaluation of each item was performed in the same manner as in example 3, except that the material lamination method was overlapped. As a result, a temperature variation of 2 ℃ at maximum occurred in the substrate, 4 minutes was required until the temperature was raised, and both the temperature variation and the temperature raising time were good. The η r retention was good at 71.7% for the surface layer and 71.8% for the inner layer. Further, the molded article was completely filled, and no resin ablation was observed, and the moldability was evaluated as ≈ o. From these results, the evaluation was evaluated as ∘ (a level at which there was no problem in actual use).

[ Table 1]

Industrial applicability

The present invention can be applied to all applications requiring extremely uniform and high-speed heating, and particularly, to a thermoplastic resin molded article having three-dimensional complicated shapes such as a high rib shape and the like, which is excellent in physical properties and surface appearance, by controlling the temperature with high accuracy in the application to thermoforming such as a thermoplastic resin sheet.

Description of the reference numerals

101 heating device

102 heating device cabinet

103 operation and control panel

104 door part

105 base material lead-in and lead-out part

106 sliding part

107 heating upper wall lifting cylinder

201 upper part casing

202 lower part casing

203 heat medium

204 saturated vapor

205 heater for heating heat medium

206 temperature sensor

207 heating the upper wall surface

208 heat the lower wall surface

209 heating chamber

210 heat insulation box

211 thermoplastic resin sheet (substrate)

501 temperature measurement Material a

502 temperature measurement Material b

503 temperature measuring point

601 laminated material for molding

Claims

1. The heating device is a heating device for heating a thermoplastic resin sheet formed of a thermoplastic resin, and is a heating device in which a wall surface of the heating device is indirectly heated by a saturated vapor of a heating medium, and a heating wall of the heating device has a lifting function, and the thermoplastic resin sheet is heated to a temperature equal to or higher than a melting point of the thermoplastic resin by contact with the heating wall.

2. The heating device according to claim 1, which has at least a self-induction function [ A ] of selectively heating a portion having a low temperature.

3. The heating device according to claim 1 or 2, wherein an organic compound is used as the heat medium.

4. The heating device according to claim 1 or 2, wherein an inorganic substance is used as the heat medium.

5. A method for producing a thermoplastic resin molded article, characterized in that a thermoplastic resin sheet made of a thermoplastic resin is heated to a temperature equal to or higher than the melting point of the thermoplastic resin by the heating device according to any one of claims 1 to 4 to be melted, and then press-molded, wherein the thermoplastic resin sheet is placed in a molding die comprising an upper die and a lower die, and after the die is closed, the pressing and cooling are carried out to solidify the thermoplastic resin sheet, thereby obtaining the thermoplastic resin molded article, wherein the heating device is a heating device in which the device wall surface is indirectly heated by a saturated vapor of a heating medium, and the heating wall has a lifting function, and the thermoplastic resin sheet is heated to a temperature equal to or higher than the melting point of the thermoplastic resin sheet by the contact of the thermoplastic resin sheet with the heating.

6. The method for producing a thermoplastic resin molded body according to claim 5, wherein 2 or more sheets of the thermoplastic resin are simultaneously melted and heated by the heating device.

7. The method for producing a thermoplastic resin molded body according to claim 6, wherein the heating device has at least a self-induction function [ A ] of selectively heating a portion having a low temperature.

8. The method for producing a thermoplastic resin molded body according to any one of claims 5 to 7, wherein the thermoplastic resin sheets having different heat capacities are arranged so as not to overlap and are melt-heated by the heating furnace.

9. The method for producing the thermoplastic resin molded body according to any one of claims 5 to 7, wherein the thermoplastic resin sheets having different heat capacities are overlapped and melt-heated by the heating furnace.

10. The method for producing a thermoplastic resin molded body according to any one of claims 5 to 9, wherein the thermoplastic resin sheet materials having different heat capacities are melted and heated, and then subjected to press molding, wherein in the press molding, the thermoplastic resin sheet materials are stacked and set in a rib-shaped molding die including an upper die and a lower die, and after clamping the die, the die is pressurized, cooled and solidified to obtain the rib-shaped thermoplastic resin molded body.

11. The method for producing a thermoplastic resin molded body according to any one of claims 5 to 9, wherein the thermoplastic resin sheet materials having different heat capacities are melted and heated, and then subjected to press molding, wherein in the press molding, the thermoplastic resin sheet materials are stacked and set in a convex-shaped molding die including an upper die and a lower die, and after clamping the die, the die is pressurized, cooled and solidified to obtain the convex-shaped thermoplastic resin molded body.

12. The method for producing a thermoplastic resin molded body according to any one of claims 5 to 11, wherein the thermoplastic resin sheet is a fiber-reinforced thermoplastic resin comprising a thermoplastic resin and a reinforcing fiber.

13. The method for producing a thermoplastic resin molded body according to claim 12, wherein the reinforcing fiber contained in the thermoplastic resin sheet contains at least 1 of carbon fiber, glass fiber, and aramid fiber.